1. Field of the Invention
The present invention relates to a press machine in which a slide is driven from its downside so as to move in the up and down direction.
2. Prior Art
As one of press machines, there is an underdrive press machine such as a dieing press machine, of which the slide is driven from the downside through a link mechanism associated with the driving means. This press machine is constructed such that the rotary motion of a crankshaft rotated by a driving source is once converted into a reciprocating motion with the help of a link mechanism such as a knuckle joint, a toggle joint and so forth, whereby a slide is correspondingly reciprocated by the converted motion in the up and down directions over the link mechanism.
In the prior press machines of this kind, however, the stroke of a slide motion in the up and down directions is limited to a preset value determined according to the sorts of press processings such as the precise press processing (low speed press processing), the stamping processing (high speed press processing) and so on.
Consequently, in the prior art press machine of this kind, the stroke of the slide can not be changed, so that the applicable range of the press machine has been limited by such limited stroke of the slide.
Therefore, in the press machine of this kind, it is important that the stroke of its slide motion in the up and down directions be made variable.